I was hoping to get some insight as to what to check next. I've searched a ton for low rail pressure errors.
The time driving to get a CEL and going into limp mode were progressively shorter to where now it immediately goes into limp mode over ~3K RPM.
Here's what I've done and tested so far:
I'm not sure what to try next. Seeing how pricey the HPFP and injectors are, I'd like to diagnose what I can to be certain of parts failures before I spend more replacing things... only for it to still not work.
If anyone has an idea what to test or try next, I'd greatly appreciate it.
The time driving to get a CEL and going into limp mode were progressively shorter to where now it immediately goes into limp mode over ~3K RPM.
Here's what I've done and tested so far:
- New fuel filter
- New auxiliary fuel pump
- New fuel pressure sensor (G247)
- New fuel pressure regulator (N276)
- The injectors' return flow is even across all four
- Return quantity at idle in 2 mins: 30 ml (spec 0-50 ml)
- Return quantity at 2~2.5K RPMs: 100 ml (spec <250 ml)
- No signs of metal wear or debris anywhere in the rail, in the HPFP lines, filter, etc.
- I was getting backflow over 2K on the original N276 regulator, resistance across the terminals was also fluctuating.
- After changing the regulator, I'm still getting backflow over 2K RPMs, where it should be zero (not sure if it's just the first few seconds it should be zero or anytime it's over 2K).
- A weird noise is coming from around the fuel filter canister (using a breaker bar as a stethoscope to contact/listen to different parts). I originally thought it was the aux pump, but after a short drive, it seems to be loudest around the canister. I'm not hearing much at the HPFP.
I'm not sure what to try next. Seeing how pricey the HPFP and injectors are, I'd like to diagnose what I can to be certain of parts failures before I spend more replacing things... only for it to still not work.
If anyone has an idea what to test or try next, I'd greatly appreciate it.